Experiences with Sculpt VC

Guido Witmond guido at witmond.nl
Tue Dec 18 00:27:55 CET 2018

Hi Genodians,

I've been playing with Sculpt VC again. Doing so thought me a lot more 
about routing.

This time I succeeded in creating a VM with partitions on two SATA 
disks. It runs Nixos inside with the /home partition on an encrypted ZFS 
mirror. (and the root partition on a virtual disk, just like the Debian VM).

When I want to start the VM and the ahci-1.part_blk is not running, the 
Runtime manager reports with a diagnostic stating vm-nixos needs 
ahci-1.part_blk. To start my vm, I inspect a different partition on that 
disk. That starts the part_blk and Runtime starts my VM.

So far so good. The problems start here:

1. When the VM runs and I stop inspecting that partition, the Runtime 
manager kills my VM.

The manager was happy to start my VM when the resource came available 
but does not keep the part_blk alive when the inspector stops.

2. When the VM runs (and has a session to the part_blk for that 
partition, I can format that partition from the Storage component. I get 
data corruption errors in ZFS on that disk. (But ZFS lives on and 
repairs it from the other mirror).

That seems to be in violation of The Book para 4.5.8:
    """The part-block component requests a single block session,
       parses a partition table,
       and hands out each partition as a separate block session to its 
       There can be one client for each partition.

I would expect that the formatter would get an error because it should 
not get a session to that partition.

Could someone shine a light on what's going on?

The log file is here: https://paste.wtmnd.nl/xfNMa3yY

I wrote a full write-up of my sculpting here: 
https://paste.wtmnd.nl/WKUQowg2 -- I intend to make it a blog post for 
others to learn from, hence the writing style.

Regards, Guido.

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